| 1. |
- Akselsson, Cecilia, et al.
(författare)
-
Weathering rates in Swedish forest soils
- 2019
-
Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 16:22, s. 4429-4450
-
Forskningsöversikt (refereegranskat)abstract
- Soil and water acidification was internationally recognised as a severe environmental problem in the late 1960s. The interest in establishing “critical loads” led to a peak in weathering research in the 1980s and 1990s, since base cation weathering is the long-term counterbalance to acidification pressure. Assessments of weathering rates and associated uncertainties have recently become an area of renewed research interest, this time due to demand for forest residues to provide renewable bioenergy. Increased demand for forest fuels increases the risk of depleting the soils of base cations produced in situ by weathering. This is the background to the research programme Quantifying Weathering Rates for Sustainable Forestry (QWARTS), which ran from 2012 to 2019. The programme involved research groups working at different scales, from laboratory experiments to modelling. The aims of this study were to (1) investigate the variation in published weathering rates of base cations from different approaches in Sweden, with consideration of the key uncertainties for each method; (2) assess the robustness of the results in relation to sustainable forestry; and (3) discuss the results in relation to new insights from the QWARTS programme and propose ways to further reduce uncertainties. In the study we found that the variation in estimated weathering rates at single-site level was large, but still most sites could be placed reliably in broader classes of weathering rates. At the regional level, the results from the different approaches were in general agreement. Comparisons with base cation losses after stem-only and whole-tree harvesting showed sites where whole-tree harvesting was clearly not sustainable and other sites where variation in weathering rates from different approaches obscured the overall balance. Clear imbalances appeared mainly after whole-tree harvesting in spruce forests in southern and central Sweden. Based on the research findings in the QWARTS programme, it was concluded that the PROFILE/ForSAFE family of models provides the most important fundamental understanding of the contribution of weathering to long-term availability of base cations to support forest growth. However, these approaches should be continually assessed against other approaches. Uncertainties in the model approaches can be further reduced, mainly by finding ways to reduce uncertainties in input data on soil texture and associated hydrological parameters but also by developing the models, e.g. to better represent biological feedbacks under the influence of climate change.
|
|
| 2. |
- Idborg, H, et al.
(författare)
-
Effects of mPGES-1 deletion on eicosanoid and fatty acid profiles in mice
- 2013
-
Ingår i: Prostaglandins & other lipid mediators. - : Elsevier BV. - 1098-8823 .- 2212-196X. ; 107, s. 18-25
-
Tidskriftsartikel (refereegranskat)abstract
- mPGES-1 is considered an alternative target for anti-inflammatory treatment with improved selectivity and safety compared to NSAIDs. mPGES-1 depletion not only suppresses inflammation via absence of inducible PGE2 but might also cause an activation of anti-inflammatory pathways. We studied effects of mPGES-1 deletion on the eicosanoid and fatty acid (FA) profiles in mice. In LPS-induced peritoneal macrophages from mPGES-1 knock-out (mPGES-1−/−, KO) mice PGE2 production was markedly attenuated, whereas levels of PGD2 metabolites (15-deoxy-Δ12,14 PGJ2 and 15-deoxy-Δ12,14 PGD2) were increased compared to wild type mice. The levels of oxidized fatty acid 13-HODE were also significantly up-regulated in KO macrophages. Significant differences in the total lipid FA composition (decrease in monounsaturated FA and increase in eicosadienoic acid) were detected in spleen of KO and WT mice. These effects of mPGES-1 deletion on eicosanoid and fatty acid metabolism have important implications for future mPGES-1 inhibitors and deserve further investigation
|
|
| 3. |
- Olsson, Petter, et al.
(författare)
-
A single step reversed-phase high performance liquid chromatography separation of polar and non-polar lipids
- 2014
-
Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1369, s. 105-115
-
Tidskriftsartikel (refereegranskat)abstract
- This paper reports a simple chromatographic system to separate lipids classes as well as their molecular species. By the use of phenyl coated silica as stationary phase in combination with a simple mobile phase consisting of methanol and water, all tested lipid classes elute within 30min. Furthermore, a method to accurately predict retention times of specific lipid components for this type of chromatography is presented. Common detection systems were used, namely evaporative light scattering detection (ELSD), charged aerosol detection (CAD), electrospray mass spectrometry (ESI-MS), and UV detection.
|
|
| 4. |
- Olsson, Petter, et al.
(författare)
-
Class separation of lipids and polycyclic aromatic hydrocarbons in normal phase high performance liquid chromatography - A prospect for analysis of aromatics in edible vegetable oils and biodiesel exhaust particulates
- 2014
-
Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1360, s. 39-46
-
Tidskriftsartikel (refereegranskat)abstract
- The retention characteristics of the major lipid components in biodiesels and edible oils as well as representative polycyclic aromatic compounds (PAHs) have been investigated on five different normal phase HPLC stationary phases, in order to optimize class separation for an automatized online HPLC cleanup of PAHs prior GC-MS analysis. By stepwise comparison of different hexane/MTBE compositions as mobile phases on cyano-, phenyl-, pentabromobenzyl-, nitrophenyl- and amino- modified silica columns, the capacity and selectivity factors for each analyte and column could be calculated. It was concluded that the most suitable column for backflush isolation of PAHs in biodiesel and edible oil matrices was the pentabromobenzyl-modified silica (PBB). A previously described online HPLC-GC-MS system using the PBB column was then evaluated by qualitative and quantitative analysis of a biodiesel exhaust particulate extract and a vegetable oil reference material. The GC-MS full scan analysis of the biodiesel particulate extract showed that the lipids had been removed from the sample and a fraction containing PAHs and oxygenated derivatives thereof had been isolated. Quantified mass fractions of PAHs of the reference material BCR-458 agreed well for most of the certified PAH mass fractions in the spiked coconut oil reference material.
|
|
| 5. |
|
|
| 6. |
- Olsson, Petter, 1981-
(författare)
-
Essentially Lipids : Analytical methods for the characterization of lipid materials
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes analytical methods for chromatographic characterizations of lipids in biological and technical systems.Lipids are a group of compounds with a central role in all known forms of life. In addition to the biological roles, lipids are also components in many products of our daily usage. The application areas include food, pharma, cosmetics, biofuels, etc.Analytical characterization of lipids is challenging since a typical lipid extract often contains several hundred unique compounds which also could vary significantly in chemical properties. Separation is in many cases crucial for identification and quantification of individual lipids and here high performance liquid chromatography (HPLC) is regarded as the technique of first choice today.In the present work, methodologies for both normal phase (NP) and reversed phase (RP) HPLC are presented. The focus has been to develop methods that are fast, have low analytical complexity and are compatible with several detection systems. Cyanopropyl coated silica was evaluated as stationary phase for NP-HPLC with the aim to separate all the lipid classes in common lipid extracts. The analytes were eluted with a binary mobile phase system based on hexane, toluene and methanol which yielded in a total runtime of 30 minutes. In a subsequent study, additional stationary phases for NP-HPLC were evaluated for online sample cleanup of polycyclic aromatic hydrocarbons (PAHs) in lipid matrixes. In the demonstrated methodology for RP-HPLC, a binary system consisting of methanol/water was utilized with phenylpropyl coated silica to elute all tested lipid classes in 30 minutes.The methodologies were compatible with various detection techniques including evaporative light scattering detection (ELSD), charged aerosol detection (CAD) as well as electrospray mass spectrometry (ESI-MS) and were applied to characterize lipid materials of both biological and technical nature.
|
|
| 7. |
- Olsson, Petter, et al.
(författare)
-
Separation And Identification Of Lipid Classes By Normal Phase Lc-Esi/Ms/Ms On A Cyanopropyl Column
- 2014
-
Ingår i: European Journal of Lipid Science and Technology. - : Wiley. - 1438-7697 .- 1438-9312. ; 116:5, s. 653-658
-
Tidskriftsartikel (refereegranskat)abstract
- In order to establish a versatile and convenient method for the analysis of lipids, electrospray ionization tandem mass spectrometry (ESI-MS/MS) was applied to a HPLC separation on a cyanopropyl-bonded stationary phase. A binary gradient mobile phase system consisting of hexane, toluene, methanol and a stable electrospray yielding sodium adduct ions could be used to generate specific product ions in MS/MS mode. By applying the LC/ESI-MS/MS method on an egg yolk sample, 29 different molecular species of phosphatidylethanolamines, phosphatidylcholines, and lysophosphatidylcholines could be detected within 25 min.
|
|
| 8. |
- Olsson, Petter, et al.
(författare)
-
Separation of Lipid Classes by HPLC on a Cyanopropyl Column
- 2012
-
Ingår i: Lipids. - : Wiley. - 0024-4201 .- 1558-9307. ; 47:1, s. 93-99
-
Tidskriftsartikel (refereegranskat)abstract
- A new method for the separation and identification of lipid classes by normal-phase HPLC on a cyanopropyl column is described. The use of a simple binary gradient, with toluene as a component, provided a rapid separation of non-polar as well as phospholipid classes. The inherent small differences in performances between possible non-polar eluent components of the gradient, such as hexane, heptane, and iso-octane, had a pronounced impact on retention times for individual phospholipid classes. Separation of molecular species within a lipid class could also be observed.
|
|
| 9. |
- Pauter, Anna M., et al.
(författare)
-
Elovl2 ablation demonstrates that systemic DHA is endogenously produced and is essential for lipid homeostasis in mice
- 2014
-
Ingår i: Journal of Lipid Research. - 0022-2275 .- 1539-7262. ; 55:4, s. 718-728
-
Tidskriftsartikel (refereegranskat)abstract
- The potential role of endogenously synthesized polyunsaturated fatty acids (PUFAs) is a highly overlooked area. Elongation of very long chain (ELOVL) fatty acids in mammals is catalyzed by the ELOVL enzymes to which the PUFA elongase ELOVL2 belongs. To determine its in vivo function, we have investigated how ablation of ELOVL2, which is highly expressed in liver, affects hepatic lipid composition and function in mice. The Elovl2 ablated mice displayed substantial decreased levels of 22:6(n3), docosahexaenoic acid (DHA), and 22:5(n6), docosapentaenoic acid (DPAn6), followed by an accumulation of 22:5(n3) and 22:4(n6) in both liver and serum showing that ELOVL2 primarily controls the elongation process of PUFAs with 22 carbons to produce 24 carbon precursors for DHA and DPA(n6) formation in vivo. The impaired PUFA levels positively influenced hepatic levels of the key lipogenic transcriptional regulator sterol regulatory element binding protein 1c (SREBP1c) as well as its downstream target genes. Surprisingly, the Elovl2 ablated mice were resistant against hepatic steatosis and diet induced weight gain implying that hepatic DHA synthesis via ELOVL2, except controlling de novo lipogenesis, also regulates lipid storage and fat mass expansion in an SREBP1c independent fashion. The changes in fatty acid metabolism were reversed by dietary supplementation with DHA.
|
|
| 10. |
- Stridbeck, Petter, et al.
(författare)
-
Partly decoupled tree-ring width and leaf phenology response to 20th century temperature change in Sweden
- 2022
-
Ingår i: Dendrochronologia. - : Elsevier BV. - 1125-7865 .- 1612-0051. ; 75
-
Tidskriftsartikel (refereegranskat)abstract
- The recent warming trend, and associated shifts in growing season length, challenge the principle of uniformitarianism, i.e., that current relations are persistent over time, and complicates the uncritical inferences of past climate from tree-ring data. Here we conduct a comparison between tree-ring width chronologies of Pinus sylvestris L. (Scots pine), Picea abies (L.) Karst. (Norway spruce) and Betula pubescens Ehrh. (Downy birch) and phenological observations (budburst and leaf senescence) of Fagus sylvatica L. (European beech), Quercus robur L. (European oak), Betula sp. (Birch), Norway spruce and Scots pine) in Sweden to assess to what extent the tree-ring width–temperature relationship and the timing of phenological phases are affected by increased temperature. Daily meteorological observations confirm a prolongation of the thermal growing season, most consistently observed as an earlier onset of around 1–2 weeks since the beginning of the 20th century. Observations of budburst closely mimic this pattern, with budburst of the deciduous trees occurring 1–2.5 weeks earlier. In contrast to the changes seen in phenology and observational temperature data, the tree-ring width–temperature relationships remain surprisingly stable throughout the 20th century. Norway spruce, Scots pine and Downy birch all show consistently significant correlations with at least one 30 day-long window of temperature starting in late June–early July season. Norway spruce displays the largest degree of stability, with a consistent 60 day-long temperature window with significant correlation starting around Julian calendar day 150. Thus, our results suggest that the principle of uniformitarianism is not violated during the period covered by modern meteorological observations. Further research is needed to determine at what thresholds the temperature sensitivity of these species may alter or deteriorate as a consequence of the ongoing climate change.
|
|
